The Great Red Spot
The Great Red Spot (GRS) is the most prominent feature of Jupiter and has been the attraction of astronomers for nearly 300 years. It was discovered by Cassini or Robert Hooke in the 17th century. The GRS is 12,000 by 25,000 kilometers and is wide enough to fit three Earths side by side. In addition to the GRS, there are similar smaller structures on the surface that act and behave in the same way.
The GRS is suspected to be a kind of massive cyclone, the result of complex interactions between high and low temperatures and pressures. Saturn and Neptune also have similar storms on the surface. Currently, scientists have been studying how these phenomena can persist for so long, but have not yet found a satisfactory answer.